The present invention relates to container closures having features for providing evidence of tampering with the closure mechanism after such tampering has occurred.
Numerous tamper-evident closures for containers have been developed in the prior art. However, each of these prior art closures suffered from one or more serious disadvantages making it less than entirely suitable for its intended purpose.
For example, one such prior art closure is applicable only to containers having radially outwardly projecting tongues adapted to extend into gaps between webs in the closure. The container, therefore, is increased in cost, and the closure must be manufactured to close tolerances. Other prior art structures similarly are unduly structurally complex or require special fittings on the containers to which they are applied, thereby greatly increasing the expense of manufacture.
Another disadvantageous structure common to several prior art closures includes a ring or seal which is broken away from the closure cap by rotating the cap in the direction of opening. The inner surface of the ring is formed with pawls adapted to mesh with teeth integrally molded onto an exterior surface of the container. Either the pawls or the ring must flex radially outwardly to prevent slippage of the pawls past the teeth when the closure is rotated in the direction of closing. Such flexure often results in a wearing away of the pawls or teeth, thereby permitting the cap to be turned in the direction of opening without breaking the ring.
Yet another mechanism found in many prior art closures is a pull tab attached to a tamper-proof ring for severing the ring away from the main body of the closure. This pull tab mechanism may be accidentally triggered during rough handling of the container and is relatively expensive to manufacture.
A further disadvantage of some other prior art closures is that they include a metal cap and ring combination fastened onto the neck of a glass bottle. After the cap is removed, the metal ring remains attached to the bottle neck, thereby making it difficult to recycle the glass bottle.